Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war against non-combatants. There are various different definitions of terrorism, with no universal agreement about it. Different definitions of terrorism emphasize its randomness, its aim to instill fear, and its broader impact beyond its immediate victims.

Non-combatant is a term of art in the law of war and international humanitarian law to refer to civilians who are not taking a direct part in hostilities; persons, such as combat medics and military chaplains, who are members of the belligerent armed forces but are protected because of their specific duties ; combatants who are placed hors de combat; and neutral persons, such as peacekeepers, who are not involved in fighting for one of the belligerents involved in a war. This particular status was first recognized under the Geneva Conventions with the First Geneva Convention of 1864.